package cn.dida.util;

import java.security.InvalidKeyException;
import java.security.SecureRandom;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
/**
 * 加密工具类
 * @author weiwei
 *
 */
public class AESEncryptor {

	private static final String AES = "AES";
	private static final int keySize = 128;
	private static final String secretKey = "111111111";
	// KeyGenerator 提供对称密钥生成器的功能，支持各种算法
	private static KeyGenerator keygen;
	// SecretKey 负责保存对称密钥
	private static SecretKey deskey;
	// Cipher负责完成加密或解密工作
	private static Cipher c;

	private AESEncryptor() {
	}

	static {
		try {
			// 实例化支持DES算法的密钥生成器(算法名称命名需按规定，否则抛出异常)
			keygen = KeyGenerator.getInstance(AES);
			keygen.init(keySize, new SecureRandom(secretKey.getBytes()));
			// 生成密钥
			deskey = keygen.generateKey();
			// 生成Cipher对象,指定其支持的DES算法
			c = Cipher.getInstance(AES);
		} catch (Exception e) {
		}
	}

	/**
	 * 对字符串加密
	 */
	public static String encrytor(String str) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
		// 根据密钥，对Cipher对象进行初始化，ENCRYPT_MODE表示加密模式
		c.init(Cipher.ENCRYPT_MODE, deskey);
		byte[] src = str.getBytes();
		return parseByte2HexStr(c.doFinal(src));
	}

	/**
	 * 对字符串解密
	 */
	public static String decryptor(String str) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
		byte[] buff = parseHexStr2Byte(str);
		// 根据密钥，对Cipher对象进行初始化，DECRYPT_MODE表示加密模式
		c.init(Cipher.DECRYPT_MODE, deskey);
		return new String(c.doFinal(buff));
	}

	/**
	 * 将二进制转换成16进制
	 */
	public static String parseByte2HexStr(byte buff[]) {
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < buff.length; i++) {
			String hex = Integer.toHexString(buff[i] & 0xFF);
			if (hex.length() == 1) {
				hex = '0' + hex;
			}
			sb.append(hex.toUpperCase());
		}
		return sb.toString();
	}

	/**
	 * 将16进制转换为二进制
	 */
	public static byte[] parseHexStr2Byte(String hexStr) {
		if (hexStr.length() < 1)
			return null;
		byte[] result = new byte[hexStr.length() / 2];
		for (int i = 0; i < hexStr.length() / 2; i++) {
			int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
			int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2), 16);
			result[i] = (byte) (high * 16 + low);
		}
		return result;
	}
	
	public static void main(String[] args) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
		System.out.println(encrytor("LTAITshIc2kCluIS"));
		System.out.println(decryptor("5B4448951EB3BFBDF4C1152C0B5DA5474E5F38AB4E0C4E7664E328B4C65FF43A").equals("znaL889uhBNf4SYhCmFNrEv14EOCTT"));
	}

}
